With the development of mobile communications technologies, an existing 2nd generation (2nd Generation, 2G) communication network gradually evolves into a 3rd generation (3rd Generation, 3G) network and even to a 4G network. As the evolving process takes a long time, a situation where the 2G network, the 3G network and the 4G network coexist occurs.
In the prior art, to efficiently use spectrums of the 2G network, a 900 MHz spectrum of a global system for mobile communications (Global System for Mobile communications, GSM) network is reframed (Reframing) to be used in a universal mobile telecommunications system (Universal Mobile Telecommunications System, UMTS) network. To ensure normal running of the existing 2G network, the prior art proposes using a UMTS bandwidth lower than the standard spectrum bandwidth 5 MHz, for example, 4.2 MHz or 4.6 MHz, on the 900 MHz spectrum.
At present, in a situation where a low bandwidth is used, a protection bandwidth between frequencies of two different types of networks (for example, the GSM and the UMTS) is insufficient. In this case, signals of a first network (for example, the GSM) may cause high interference to a second network (for example, the UMTS).